The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From be4f3b3f82271c3193ce200a996dc70682c8e622 Mon Sep 17 00:00:00 2001 From: Xiaoyao Li xiaoyao.li@intel.com Date: Wed, 26 Jan 2022 17:22:24 +0000 Subject: [PATCH] KVM: x86: Keep MSR_IA32_XSS unchanged for INIT

It has been corrected from SDM version 075 that MSR_IA32_XSS is reset to zero on Power up and Reset but keeps unchanged on INIT.

Fixes: a554d207dc46 ("KVM: X86: Processor States following Reset or INIT") Cc: stable@vger.kernel.org Signed-off-by: Xiaoyao Li xiaoyao.li@intel.com Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20220126172226.2298529-2-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a50baf4c5bff..b6d60c296eda 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -11266,6 +11266,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) vcpu->arch.msr_misc_features_enables = 0;

vcpu->arch.xcr0 = XFEATURE_MASK_FP; + vcpu->arch.ia32_xss = 0; }

/* All GPRs except RDX (handled below) are zeroed on RESET/INIT. */ @@ -11282,8 +11283,6 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) cpuid_0x1 = kvm_find_cpuid_entry(vcpu, 1, 0); kvm_rdx_write(vcpu, cpuid_0x1 ? cpuid_0x1->eax : 0x600);

- vcpu->arch.ia32_xss = 0; - static_call(kvm_x86_vcpu_reset)(vcpu, init_event);

kvm_set_rflags(vcpu, X86_EFLAGS_FIXED);